#include <fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int n,m,M,r,s[19],i,j,l[17],c[17],a[17][17];
int main()
{f>>n>>m;
for(i=1;i<=n;++i)
    for(j=1;j<=m;++j)
        f>>a[i][j];
for(i=1;i<=n;++i)
    if(l[i]<0)
        for(j=1;j<=m;++j)a[i][j]=-a[i][j];
for(i=1;i<=n;++i)
    for(j=1;j<=m;++j)c[j]+=a[i][j];
for(j=1;j<=m;++j)
    if(c[j]<0)
        for(i=1;i<=n;++i)a[i][j]=-a[i][j];
for(i=1;i<=n;++i)
    for(j=1;j<=m;++j)s[1]+=a[i][j];
r=1;
do{r++;
for(i=1;i<=n;++i)
    for(j=1;j<=m;++j)l[i]+=a[i][j];
for(i=1;i<=n;++i)
    if(l[i]<0)
        for(j=1;j<=m;++j)a[i][j]=-a[i][j];
for(i=1;i<=n;++i)
    for(j=1;j<=m;++j)c[j]+=a[i][j];
for(j=1;j<=m;++j)
    if(c[j]<0)
        for(i=1;i<=n;++i)a[i][j]=-a[i][j];
for(i=1;i<=n;++i)
    for(j=1;j<=m;++j)s[r]+=a[i][j];


}while(s[r]>s[r-1]);
for(i=1;i<=19;++i)
    if(M<s[i])M=s[i];
g<<M;
    return 0;
}